﻿#include <linux/module.h>
#include <linux/poll.h>

#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/fcntl.h>
#include <linux/timer.h>

#define DRV_FILE "drv_template2"
#define CHR_DEV_NAME "harry_template2"
#define COMPITABLE_NAME "100ask,gpiodemo"
#define PDRV_NAME "100ask,gpiodemo"

struct gpio_desc
{
	int gpio;
	int irq;
	char name[128];
	int key;
	struct timer_list timer;
};

static struct gpio_desc *gpios;
static int count;

/* 主设备号 */
static int major = 0;
static struct class *gpio_class;

/* 环形缓冲区 */
#define BUF_LEN 128
static int g_datas[BUF_LEN];
static int r, w;

struct fasync_struct *button_fasync;

#define NEXT_POS(x) ((x + 1) % BUF_LEN)

static int is_data_buf_empty(void)
{
	return (r == w);
}

static int is_data_buf_full(void)
{
	return (r == NEXT_POS(w));
}

static void put_data(int key)
{
	if (!is_data_buf_full())
	{
		g_datas[w] = key;
		w = NEXT_POS(w);
	}
}

static int get_data(void)
{
	int key = 0;
	if (!is_data_buf_empty())
	{
		key = g_datas[r];
		r = NEXT_POS(r);
	}
	return key;
}

static DECLARE_WAIT_QUEUE_HEAD(gpio_wait);

// static void timer_expire(struct timer_list *t)
static void timer_expire(unsigned long data)
{
	/* data ==> gpio */
	// struct gpio_desc *gpio_desc = from_timer(gpio_desc, t, timer);
	struct gpio_desc *gpio_desc = (struct gpio_desc *)data;
	int val;
	int key;

	val = gpio_get_value(gpio_desc->gpio);

	// printk("timer_expire key %d %d\n", gpio_desc->gpio, val);
	key = (gpio_desc->key) | (val << 8);
	put_data(key);
	wake_up_interruptible(&gpio_wait);
	kill_fasync(&button_fasync, SIGIO, POLL_IN);
}

/* 实现对应的open/read/write等函数，填入file_operations结构体                   */
static ssize_t gpio_drv_read(struct file *file, char __user *buf, size_t size, loff_t *offset)
{
	// printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	int err;
	int key;

	if (is_data_buf_empty() && (file->f_flags & O_NONBLOCK))
		return -EAGAIN;

	wait_event_interruptible(gpio_wait, !is_data_buf_empty());
	key = get_data();
	err = copy_to_user(buf, &key, 4);

	return 4;
}

static ssize_t gpio_drv_write(struct file *file, const char __user *buf, size_t size, loff_t *offset)
{
	unsigned char ker_buf[2];
	int err;

	if (size != 2)
		return -EINVAL;

	err = copy_from_user(ker_buf, buf, size);

	if (ker_buf[0] >= sizeof(gpios) / sizeof(gpios[0]))
		return -EINVAL;

	gpio_set_value(gpios[ker_buf[0]].gpio, ker_buf[1]);
	return 2;
}

static unsigned int gpio_drv_poll(struct file *fp, poll_table *wait)
{
	// printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	poll_wait(fp, &gpio_wait, wait);
	return is_data_buf_empty() ? 0 : POLLIN | POLLRDNORM;
}

static int gpio_drv_fasync(int fd, struct file *file, int on)
{
	if (fasync_helper(fd, file, on, &button_fasync) >= 0)
		return 0;
	else
		return -EIO;
}

/* 定义自己的file_operations结构体                                              */
static struct file_operations gpio_key_drv = {
	.owner = THIS_MODULE,
	.read = gpio_drv_read,
	.write = gpio_drv_write,
	.poll = gpio_drv_poll,
	.fasync = gpio_drv_fasync,
};

static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{
	struct gpio_desc *gpio_desc = dev_id;
	printk("gpio_key_isr key %d irq happened\n", gpio_desc->gpio);
	mod_timer(&gpio_desc->timer, jiffies + HZ / 5);
	return IRQ_HANDLED;
}

/* 在入口函数 */
static int gpio_drv_probe(struct platform_device *pdev)
{
	int err = 0;
	int i;
	struct device_node *np = pdev->dev.of_node;
	struct resource *res;

	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);

	/* 从platfrom_device获得引脚信息
	 * 1. pdev来自c文件
	 * 2. pdev来自设备树
	 */

	if (np)
	{
		/* pdev来自设备树 : 示例
		reg_usb_ltemodule: regulator@1 {
			compatible = "100ask,gpiodemo";
			gpios = <&gpio5 5 GPIO_ACTIVE_HIGH>, <&gpio5 3 GPIO_ACTIVE_HIGH>;
		};
		*/
		count = of_gpio_count(np);
		if (!count)
			return -EINVAL;

		gpios = kmalloc(count * sizeof(struct gpio_desc), GFP_KERNEL);
		for (i = 0; i < count; i++)
		{
			gpios[i].gpio = of_get_gpio(np, i);
			sprintf(gpios[i].name, "%s_pin_%d", np->name, i);
		}
	}
	else
	{
		/* pdev来自c文件
		static struct resource omap16xx_gpio3_resources[] = {
			{
					.start  = 115,
					.end    = 115,
					.flags  = IORESOURCE_IRQ,
			},
			{
					.start  = 118,
					.end    = 118,
					.flags  = IORESOURCE_IRQ,
			},		};
		*/
		count = 0;
		while (1)
		{
			res = platform_get_resource(pdev, IORESOURCE_IRQ, count);
			if (res)
			{
				count++;
			}
			else
			{
				break;
			}
		}

		if (!count)
			return -EINVAL;

		gpios = kmalloc(count * sizeof(struct gpio_desc), GFP_KERNEL);
		for (i = 0; i < count; i++)
		{
			res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
			gpios[i].gpio = res->start;
			sprintf(gpios[i].name, "%s_pin_%d", pdev->name, i);
		}
	}

	for (i = 0; i < count; i++)
	{
		gpios[i].irq = gpio_to_irq(gpios[i].gpio);

		setup_timer(&gpios[i].timer, timer_expire, (unsigned long)&gpios[i]);
		// timer_setup(&gpios[i].timer, timer_expire, 0);
		gpios[i].timer.expires = ~0;
		add_timer(&gpios[i].timer);
		err = request_irq(gpios[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "100ask_gpio_key", &gpios[i]);
	}

	/* 注册file_operations 	*/
	major = register_chrdev(0, CHR_DEV_NAME, &gpio_key_drv); /* /dev/gpio_desc */

	gpio_class = class_create(THIS_MODULE, "100ask_gpio_key_class");
	if (IS_ERR(gpio_class))
	{
		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
		unregister_chrdev(major, CHR_DEV_NAME);
		return PTR_ERR(gpio_class);
	}

	device_create(gpio_class, NULL, MKDEV(major, 0), NULL, "100ask_gpio"); /* /dev/100ask_gpio */

	return err;
}

/* 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数
 */
static int gpio_drv_remove(struct platform_device *pdev)
{
	int i;

	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	// 卸载时释放已分配的内存
	if (gpios)
	{
		for (i = 0; i < count; i++)
		{
			free_irq(gpios[i].irq, &gpios[i]);
			del_timer(&gpios[i].timer);
		}
		kfree(gpios); // 释放通过 kmalloc 分配的内存
	}
	device_destroy(gpio_class, MKDEV(major, 0));
	class_destroy(gpio_class);
	unregister_chrdev(major, CHR_DEV_NAME);

	for (i = 0; i < count; i++)
	{
		free_irq(gpios[i].irq, &gpios[i]);
		del_timer(&gpios[i].timer);
	}

	return 0;
}

static const struct of_device_id gpio_dt_ids[] = {
	{
		.compatible = COMPITABLE_NAME,
	},
	{/* sentinel */}};

static struct platform_driver gpio_platform_driver = {
	.driver = {
		.name = PDRV_NAME,
		.of_match_table = gpio_dt_ids,
	},
	.probe = gpio_drv_probe,
	.remove = gpio_drv_remove,
};

static int __init gpio_drv_init(void)
{
	/* 注册platform_driver */
	return platform_driver_register(&gpio_platform_driver);
}

static void __exit gpio_drv_exit(void)
{
	/* 反注册platform_driver */
	platform_driver_unregister(&gpio_platform_driver);
}

/* 7. 其他完善：提供设备信息，自动创建设备节点                                     */

module_init(gpio_drv_init);
module_exit(gpio_drv_exit);

MODULE_LICENSE("GPL");
